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  2. Resolution (chromatography) - Wikipedia

    en.wikipedia.org/wiki/Resolution_(chromatography)

    where t R is the retention time and w b is the peak width at baseline. The bigger the time-difference and/or the smaller the bandwidths, the better the resolution of the compounds. The bigger the time-difference and/or the smaller the bandwidths, the better the resolution of the compounds.

  3. Aggregate function - Wikipedia

    en.wikipedia.org/wiki/Aggregate_function

    In order to calculate the average and standard deviation from aggregate data, it is necessary to have available for each group: the total of values (Σx i = SUM(x)), the number of values (N=COUNT(x)) and the total of squares of the values (Σx i 2 =SUM(x 2)) of each groups. [8]

  4. Hydraulic conductivity - Wikipedia

    en.wikipedia.org/wiki/Hydraulic_conductivity

    Allen Hazen derived an empirical formula for approximating hydraulic conductivity from grain-size analyses: = where Hazen's empirical coefficient, which takes a value between 0.0 and 1.5 (depending on literature), with an average value of 1.0. A.F. Salarashayeri & M. Siosemarde indicate C is usually between 1.0 and 1.5, with D in mm and K in cm/s.

  5. Johnson's parabolic formula - Wikipedia

    en.wikipedia.org/wiki/Johnson's_parabolic_formula

    In structural engineering, Johnson's parabolic formula is an empirically based equation for calculating the critical buckling stress of a column. The formula is based on experimental results by J. B. Johnson from around 1900 as an alternative to Euler's critical load formula under low slenderness ratio (the ratio of radius of gyration to ...

  6. Richardson extrapolation - Wikipedia

    en.wikipedia.org/wiki/Richardson_extrapolation

    A (1, 1) = Trapezoidal (f, tStart, tEnd, h, y0) % Each row of the matrix requires one call to Trapezoidal % This loops starts by filling the second row of the matrix, % since the first row was computed above for i = 1: maxRows-1 % Starting at i = 1, iterate at most maxRows - 1 times % Halve the previous value of h since this is the start of a ...

  7. R-value (soils) - Wikipedia

    en.wikipedia.org/wiki/R-value_(soils)

    The R-Value test [1] measures the response of a compacted sample of soil or aggregate to a vertically applied pressure under specific conditions. This test is used by Caltrans for pavement design, replacing the California bearing ratio test. Many other agencies have adopted the California pavement design method, and specify R-Value testing for ...

  8. Perry–Robertson formula - Wikipedia

    en.wikipedia.org/wiki/Perry–Robertson_formula

    The Perry–Robertson formula is a mathematical formula which is able to produce a good approximation of buckling loads in long slender columns or struts, and is the basis for the buckling formulation adopted in EN 1993. The formula in question can be expressed in the following form:

  9. OLAP cube - Wikipedia

    en.wikipedia.org/wiki/OLAP_cube

    Slice is the act of picking a rectangular subset of a cube by choosing a single value for one of its dimensions, creating a new cube with one fewer dimension. [5] The picture shows a slicing operation: The sales figures of all sales regions and all product categories of the company in the year 2005 and 2006 are "sliced" out of the data cube.